Epidemic evidence and animal studies suggested that hypothyroidism is related with maternal pregnancy outcome, offspring cognitive ability. Negro's study found improved maternal health in those screened in early trimester; while Lazarus et al. reported no significant offspring IQ score at 3yrs in universal screening in early trimester. Currently, it lacks evidence of universal pre-conception screening for maternal pregnancy outcome and offspring cognitive development, motivation ability, attention. China Governmental Health Department has included thyroid function screening into preconception in 2011. The investigators hypothesize that pre-conception effective treatment may be helpful for decrease possible negative effects on maternal and offspring health, instead of early trimester.